Declare Function GetUserName Lib "advapi32.dll" Alias "GetUserNameA" (ByVal lpBuffer As String, nSize As Long) As Long
Function getName() As String
    Dim sBuffer As String
    Dim lSize As Long
    sBuffer = Space$( 255 )
    lSize = Len(sBuffer)
    Call GetUserName(sBuffer, lSize)
    sBuffer = LTrim(RTrim(sBuffer))
    lSize = Len(sBuffer)
    If lSize >  0  Then ' Если пользователь определен
         getName = sBuffer
    Else
         getName = "Не определен"
    End If
End Function